The present invention relates to a semiconductor laser and, more particularly, to a V-channeled substrate inner stripe (VSIS) laser.
Recently, semiconductor lasers are used as light sources in an optical information processing systems utilizing devices such as optical video discs, optical audio discs, and laser printers. In such systems, the semiconductor laser must operate at a low threshold current, must emit a beam of a shorter wavelength with a stable transverse mode, and must enjoy a long operating life.
A V-channeled substrate inner stripe (VSIS) laser has been developed, which is suited to fulfill the above-mentioned requirements. However, the conventional VSIS laser can not show the satisfying operating life period because of a compressive stress applied to an active layer thereof.
Accordingly, an object of the present invention is to provide a V-channeled substrate inner stripe (VSIS) laser which stably operates at a shorter wavelength.
Another object of the present invention is to provide a semiconductor laser, wherein the compressive stress applied to an active layer is minimized.
Other objects and further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. It should be understood, however, that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.
To achieve the above objects, pursuant to an embodiment of the present invention, a GaAs layer is formed on a GaAs substrate. An n-GaAs current blocking layer, a p-GaAlAs cladding layer, a p-GaAlAs active layer, and an n-GaAlAs cladding layer are formed on the GaAs layer. An n-GaAlAs cap layer is formed on the n-GaAlAs cladding layer. The n-GaAlAs cap layer is thick enough so as to support the semiconductor laser. After formation of the n-GaAlAs cap layer, the GaAs substrate is removed through the use of an etching method.
The compressive stress applied to the active layer is mainly caused by the difference of the lattice constant between the GaAs substrate and the p-GaAlAs active layer at room temperature. When the GaAs substrate is removed, the compressive stress applied to the active layer is minimized.
In a preferred form, a GaAlAs etching stop layer is disposed between the GaAs substrate and the GaAs layer in order to ensure a stable etching of the GaAs substrate. After removing the GaAs substrate, the GaAlAs etching stop layer is removed by another etchant.